1. Field of the Invention
The present invention relates to an injection molding apparatus for producing plastic products having grain patterns thereon.
2. Background Art
Conventionally, plastic products having grained surfaces have been produced by preparing a laminate material with a grain pattern on its surface in advance, and then the laminate material is adhered using an adhesive or the like to the surface of the plastic product. However, when there are three-dimensional curved surfaces or the like on the products, this method has a problem in that the laminate material is stretched unnecessarily or that wrinkles occur around the curved surfaces. There is also a problem in that there is stretching or sagging in the grain pattern itself.
In order to solve these problems, a method for producing a plastic product having a grained surface has been proposed. According to this method, a grain pattern is formed in advance in one die, and a laminate material for creating the grain pattern is placed in this die. Under this condition, a plastic product formed in a predetermined shape and coated with adhesive is pushed against the back surface of the laminate material such that the laminate material is caused to adhere to the product. Thereafter, the laminate material is pulled by a vacuum from the die having the grain pattern thereon. However, this grained pattern fabrication process has a problem in that it takes too long.
Under the above situation, what is needed is a method wherein grain patterns can be fabricated rapidly on the plastic product in a single unit, and an injection molding apparatus that can be used for that purpose.